Rui Costa of Portugal prevailed over a star-studded field to win a gruelling
road race at the World Road Championships Sunday, edging Joaquim Rodríguez
of Spain in a two-up sprint finish.

Rodríguez attacked several times in the final lap of a hilly circuit but Rui Costa caught him in the finishing straight and easily won the sprint for the biggest victory of his career.

Rui Costa clocked 7 hours 25 minutes 43 seconds over the 272-kilometre route to become the first Portuguese winner in the race's 86-year history.

The 26-year-old Costa has won three stages at the Tour de France, one in 2011 and two this year, and he also won the Tour de Suisse this year and last. He is a team-mate of Valverde's on the Movistar trade team.

Rodríguez crossed with the same time and Alejandro Valverde of Spain edged local favourite Vincenzo Nibali of Italy for third, 17 seconds behind.

The course started in Lucca near the coast and ended with 10 laps of a difficult 16.6-kilometre circuit in and around Florence.

For more than six hours, riders raced through heavy rain. But the sun eventually came out and dried the course for the final lap.

The circuit's highlights were one long climb, a 4.4-kilometre ascent to the scenic town of Fiesole with an average gradient of 5 per cent, then after a brief but technical descent another short but steep climb of 600 metres with gradients as high as 16 per cent.

With the constant climbing and descending, some riders compared it to a rollercoaster.

Despite the rain, fans turned out in large numbers, especially when riders passed by Florence's Duomo cathedral and wound their way through the city's medieval streets. There were also big crowds on the climbs.

Five riders broke away from the pack soon after the start and established a lead of seven minutes at one point. But the main pack began to pick up the pace as it entered the circuit and of the original five – Bartosz Huzarski (Poland), Rafaa Chtioui (Tunisia), Yonder Godoy (Venezuela), Matthias Brandle (Austria) and Jan Barta (Czech Republic) – only Barta and Huzarski were left in front after five laps.

Huzarski was the lone leader when Italy's Giovanni Visconti caught up with him during the eighth lap.

Italy set the pace for the first few laps of the circuit, then Belgium took over and caught the leaders in the penultimate lap.

A pack of about 50 riders was in the lead entering the final lap. Then the attacks began, first by Italy's Michele Scarponi on the Fiesole climb, then by Nibali, and finally with Rodríguez and Costa.

Pre-race favourites Peter Sagan and Fabian Cancellara couldn't respond to Scarponi's attack and were left behind.

With riders not permitted to wear two-way radios, they were advised of their status by team helpers along the side of the road holding up info boards.

There were several crashes. One, on the second lap of the circuit, forced 2009 winner Cadel Evans of Australia to withdraw. On the final lap, Rigoberto Urán of Colombia crashed hard.

It was a race to forget for what was considered a strong British team featuring the last two Tour de France winners, Sir Bradley Wiggins and Chris Froome, plus sprinter Mark Cavendish.

Of the eight British starters, none finished.

After seeing team-mate Wiggins crash out following a multi-rider incident in wet conditions, Froome later decided to abandon his race early.

"Bad day for me today," Froome tweeted. "Really tough circuit under these conditions."

"There was a long way to go still and I knew it wasn't the day today," he said.

"This has been a really big target for me. I've trained really hard for this. It is disappointing and to not be up there now."

Froome will, however, be able to reflect on a season that was highlighted most obviously by his success at the 100th Tour de France this summer.

"It's disappointing but having said that I've got to bear in mind that this has been an amazing season for me regardless," he said.

"This would have been a fantastic way to end it off but it is not to be."

Following the crash, Cycling Australia confirmed on its Twitter account that former Tour de France winner Cadel Evans and David Tanner had "both been taken to hospital for precautionary scans of leg injuries".

Also, it was announced that Jonathan Tiernan-Locke, who withdrew from the British team earlier this week, was notified by the UCI of a potential discrepancy in his biological passport data.